7 ms·

The Geography of Radionavigation and the Politics of Intangible Artifacts (2014) [pdf]

9 points by benbreen 11y ago

maxden 11y ago
Thanks for submitting this. I find the technology developed during WW2 to be quite advanced for the time, as I guess most secret/military technology is. When the Allies discovered the Germans attacking based on beams, they would either attempt to bend them or send in an attack following the beam back to transmitter. With the use of 'Gee', until there were transmitters within France, the Germans would jam the signal such that shortly after crossing the French coast, the signal was obscured in what they described as 'grass' along the bottom of the signal trace. Navigators would also take star shots outside of Gee range. Quite a few of the transmitter sites, chosen for their geography, are still in use for similar purposes today. The development of H2S the ground mapping radar and also utilizing any radar return before it hit the ground gave them 'fishpond' which would display a return for an aircraft that was below them. That could either be another bomber in the stream or a night fighter coming in for an attack.
Animats 11y ago
That's a fun read. The LORAN systems were the ones that really put a grid (or rather sets of intersecting hyperbolas) on the world, because they were so long range, usable out to 1500 miles from the stations. The article is mostly about the European theater, but navigation was a much more difficult problem in the Pacific, where the distances over water were great and the islands were small and easily missed. LORAN was the first system that put an end to being totally lost. The US airways system predated radio navigation. The first US airways used very bright rotating beacons every 30 miles or so, so flyers on the airway could fly from beacon to beacon. Remnants of that system live on as the white and green beacons rotating beacons seen at US airports today. The radio system was an upgrade to the beacon system. Beam type systems remain, mostly as VORs, VHF Omnirange stations. They're usually at airports, and they cover several acres and require clear space around them, much to the annoyance of people who would like to develop the real estate. The most visible one in Silicon Valley is at Trimble Rd and US 101, next to SJC. The basic signal it sends can be visualized as a big flash followed by a rotating beam. The time between the two gives the bearing from the station. VORs also have Distance Measuring Equipment, so they can be interrogated and will reply, with the return time giving distance. This is still the primary way aircraft find airports. With VORs, the error decreases as you get closer, so the accuracy is very good as you are lining up for the runway. The FAA wants to shut down about half the VORs in the US.[1] The ones at major airports will remain, but some intermediate locations will lose their VOR. This worries some people, because it leads to over-dependence on GPS. [1] http://www.faa.gov/air_traffic/flight_info/aeronav/acf/media/Presentations/12-01_Discon-of-VOR-update.pdf http://www.faa.gov/air_traffic/flight_info/aeronav/acf/media...

9 points by benbreen 11y ago

Thanks for submitting this. I find the technology developed during WW2 to be quite advanced for the time, as I guess most secret/military technology is. When the Allies discovered the Germans attacking based on beams, they would either attempt to bend them or send in an attack following the beam back to transmitter. With the use of 'Gee', until there were transmitters within France, the Germans would jam the signal such that shortly after crossing the French coast, the signal was obscured in what they described as 'grass' along the bottom of the signal trace. Navigators would also take star shots outside of Gee range. Quite a few of the transmitter sites, chosen for their geography, are still in use for similar purposes today. The development of H2S the ground mapping radar and also utilizing any radar return before it hit the ground gave them 'fishpond' which would display a return for an aircraft that was below them. That could either be another bomber in the stream or a night fighter coming in for an attack.

Animats 11y ago

That's a fun read. The LORAN systems were the ones that really put a grid (or rather sets of intersecting hyperbolas) on the world, because they were so long range, usable out to 1500 miles from the stations. The article is mostly about the European theater, but navigation was a much more difficult problem in the Pacific, where the distances over water were great and the islands were small and easily missed. LORAN was the first system that put an end to being totally lost. The US airways system predated radio navigation. The first US airways used very bright rotating beacons every 30 miles or so, so flyers on the airway could fly from beacon to beacon. Remnants of that system live on as the white and green beacons rotating beacons seen at US airports today. The radio system was an upgrade to the beacon system. Beam type systems remain, mostly as VORs, VHF Omnirange stations. They're usually at airports, and they cover several acres and require clear space around them, much to the annoyance of people who would like to develop the real estate. The most visible one in Silicon Valley is at Trimble Rd and US 101, next to SJC. The basic signal it sends can be visualized as a big flash followed by a rotating beam. The time between the two gives the bearing from the station. VORs also have Distance Measuring Equipment, so they can be interrogated and will reply, with the return time giving distance. This is still the primary way aircraft find airports. With VORs, the error decreases as you get closer, so the accuracy is very good as you are lining up for the runway. The FAA wants to shut down about half the VORs in the US.[1] The ones at major airports will remain, but some intermediate locations will lose their VOR. This worries some people, because it leads to over-dependence on GPS. [1] http://www.faa.gov/air_traffic/flight_info/aeronav/acf/media/Presentations/12-01_Discon-of-VOR-update.pdf http://www.faa.gov/air_traffic/flight_info/aeronav/acf/media...